Sgisela I was wondering the same!
I think most common vinyl wraps are dry-applied. it's a film with a sticky backing that you peel and stick, and you don't need to "paint" on any glue. But there are a lot of exceptions, and some films use water and other liquids for a wet application (hopefully not on a piano!). That gummy goop all over the keys though, I have no idea what that is, or what kind of drinks would be that viscous after the alcohol and water evaporate. Is there a drink that's 2 cups of pure sugar mixed with a shot of Bacardi?
I remember there was discussion here about what kind of player system was installed, and I was glad to see in the video a closeup of the control module, showing it's a QRS. But the piano tech in the video doesn't seem to do much work with player/silent systems, and didn't talk about it at all. But you can see the plungers from the key solenoids sticking up from the back of the keybed cavity.
I think you're right that the piano must have a TON of player hours on it, at an airport I suspect they just had it self-play all day, every day until it stopped working!
The piano tuner in the video seems like a great guy. I've been watching his videos and he's a young guy trying really hard to build a new business around something he loves, and he share what he's learning, including how much he makes in typical day, etc. Really wishing him the best.